DESCRIPTION
In a pressure vessel known from DE-OS No. 30 07 524 the outer surface of a blow-moulded plastic inner vessel determines the outer shape of the finished pressure vessel. The inner vessel has an open spigot extension and a cambered bottom. Applied to both ends of the inner vessel are strengthening caps, one of which has a collar surrounding the spigot extension of the inner vessel, while the other one has an outwards projecting pin. The strengthening caps act as auxiliary winding bodies formed with a recessed collar or shoulder, respectively, whereat the winding pitch is reversed as an outer winding layer is helically wound onto the inner vessel. In manufacturing a pressure vessel of this type, a single inner vessel with its strengthening caps is mounted in a winding apparatus to have the outer winding layer applied thereto, i.e. the pressure vessels are individually finished one after another. A disadvantage of this method is the expense for making the inner vessel which in the finished pressure vessel substantially acts as a lost core, but has nevertheless to be accurately shaped to determine the shape and desired volume of the finished pressure vessel. The costs for making the inner vessel and its strengthening caps contribute considerably to the overall all costs for the finished pressure vessel.
In a method for making a pressure vessel as known from DE-OS No. 28 07 966, an inner plastic vessel is likewise formed in a blow-moulding process and has strengthening caps applied to its ends before having a winding layer of glass fibre reinforced plastic wound thereon. Also in this case considerable costs are incurred for making the inner vessel, so that the costs for the inner vessel constitute a disproportional factor of the overall cost of the finished pressure vessel.
Described in a publicity leaflet issued in 1984 by the firm of Singer Controls Division, 9655 Soreng Ave, Ill., USA, under the title "Mobile Air Conditioning Service Bulletin" is a metal pressure vessel for use as a drier vessel in vehicle air conditioning installations. This pressure vessel is made of draw-moulded steel sheet upper and lower container halves joined to one another by welding. The most important disadvantage of this pressure vessel is its relatively heavy weight which is considered particularly disadvantageous in a vehicle air conditioning installation.